Iggy Azalea feat. Charlie XCX, 'Fancy'

Iggy Azalea, with the help of Charli XCX, kicked off the performances with 'Fancy' on a prom-themed set. The blonde rapper wore a yellow plaid dress with a full skirt, looking like quite the Prom Queen as she danced her way around the stage. She did have a few technical difficulties at the beginning, but she pulled it off --- and looked and sounded fabulous while doing so.

Cody Simpson, 'Surfboard'

Cody Simpson stole the show with 'Surfboard!' Dressed in a simple black jacket and white T-shirt, the 17-year-old singer played the first part of the song on his guitar while his backup dancers performed behind him. As a tribute to his spot on 'Dancing With the Stars' earlier in the season, Cody traded in his guitar for his dance partner, pulling out a dance number that proved he hasn't yet forgotten everything he learned on the show.

Ariana Grande, 'Problem'

The pop star looked smokin' when she appeared on stage in a black crop top and leggings while perched on a motorcycle. She quickly ditched the bike to dance around the stage with her leather jacket-clad backup dancers. Like usual, Ariana hit those insane notes at the end of 'Problem' without even pausing her moves. We wouldn't expect anything less!

Amber Riley, 'Colorblind' and 'Do Your Thing'

Last season's 'Dancing With the Stars' winner Amber Riley made her return to the dance floor to perform 'Do Your Thing' and her new single 'Colorblind.' Viewers were only shown a short snippet of 'Colorblind,' but Amber shined later on when she came back in head-to-toe gold for her second song. Her '20s inspired, jazz-influenced performance got everybody out of their seats.

Christina Perri, 'Human'

Christina Perri wrapped up the show with a moving performance of 'Human.' Dressed in white and seated behind an all-white piano, she belted out the ballad beautifully. Big screens behind the singer played highlights from this past season of 'Dancing With the Stars,' creating an emotional backdrop for an emotional song.